Glycosyltransferases catalyze the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. The acceptor molecule can be a lipid, a protein, a heterocyclic compound, or another carbohydrate residue. The structures of the formed glycoconjugates are extremely diverse, reflecting a wide range of biological functions. The members of this family share a common GTB topology, one of the two protein topologies observed for nucleotide-sugar-dependent glycosyltransferases. GTB proteins have distinct N- and C- terminal domains each containing a typical Rossmann fold. The two domains have high structural homology despite minimal sequence homology. The large cleft that separates the two domains includes the catalytic center and permits a high degree of flexibility.

argininosuccinate synthase. argG in bacteria, ARG1 in Saccharomyces cerevisiae. There is a very unusual clustering in the alignment, with a deep split between one cohort of E. coli, H. influenzae, and Streptomyces, and the other cohort of eukaryotes, archaea, and the rest of the eubacteria [Amino acid biosynthesis, Glutamate family].

This family is most closely related to the GT1 family of glycosyltransferases. The yeast gene ALG1 has been shown to function as a mannosyltransferase that catalyzes the formation of dolichol pyrophosphate (Dol-PP)-GlcNAc2Man from GDP-Man and Dol-PP-Glc-NAc2, and participates in the formation of the lipid-linked precursor oligosaccharide for N-glycosylation. In humans ALG1 has been associated with the congenital disorders of glycosylation (CDG) designated as subtype CDG-Ik.

transferase, transferring glycosyl groups